Science Thread: Review of Audioquest Jitterbug and Uptone Regen USB Conditioners

Kal Rubinson

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May 5, 2010
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Mike Lavigne

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Would you like to loan me your Jcat to see how much it improves the performance relative to built-in USB port? Was going to buy one just now but fell off my chair when I saw the 400 Euro price!!!
I have one of those JCat USB cards with their battery power supply, and the Uptone LPS for the Regen too, here locally if you can bring your testing gear to my room you are welcome to measure it....when I return from RMAF next week.
 

Elberoth

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Would you like to loan me your Jcat to see how much it improves the performance relative to built-in USB port? Was going to buy one just now but fell off my chair when I saw the 400 Euro price!!!
Arim,

I'm afraid back and forth shipping to the US from Poland would be like $150 both ways plus lots of paperwork (unless you are willing to pay 30% of VAT + duty its way back to the EU).

But maybe there is chance to borrow the SOtM card ? Or buy one if it comes with money back guarantee ?
 

Elberoth

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I have one of those JCat USB cards with their battery power supply, and the Uptone LPS for the Regen too, here locally if you can bring your testing gear to my room you are welcome to measure it....when I return from RMAF next week.
Mike, the Jcat battery PSU should power the SSD - and nothing more. For whatever reason, the Jcat card works better with quality linear PSU.
 
Apr 3, 2010
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I have one of those JCat USB cards with their battery power supply, and the Uptone LPS for the Regen too, here locally if you can bring your testing gear to my room you are welcome to measure it....when I return from RMAF next week.
Oh, that is a possibility. The Audio Precision is a large box but still can be carried. Let's sync up when we both get back then. Thanks Mike.
 
Apr 3, 2010
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As a USB source I'm using a small Sony Pocket PC (VGN-UX380) and the USB connected via its docking station - running WinXP SP3.
He is using that???



That is definitely not representative of larger class of PCs. Wonder why he is not testing with another PC. Surely he has more equipment than that???
 

Mike Lavigne

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Mike, the Jcat battery PSU should power the SSD - and nothing more. For whatever reason, the Jcat card works better with quality linear PSU.
sorry; I get all confused on what goes to what.

the Uptone JS-2 arrived today at work. I brought in my CAPS v4 CPU, the Teradak and that battery power supply for the SATA card. he will put it all together so I can listen to the finished product tonight.
 

Mike Lavigne

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mansr

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I think this category is going to explode. I would be shocked if in a year we did not have 20-30 different units if not more. They are so easy to build and seemingly such easy sale that anyone with a soldering iron and screwdriver practically will build one :).
They don't even need to do anything, apparently.
 

BE718

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Oct 1, 2015
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Hi

I also tried the Regen with a 9 volt battery and it made no difference to the spuria. I am making the presumption this is the USB 8kHz data packet noise getting through and nothing to do with the SMPS.
 
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BE718

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Now we are getting somewhere ! Those jitter spikes that were barely visible on Amir's measurements, can be seen clearly when the noise floor was lowered.

A Q to Amir: the high noise floor on your measurements, is the limitation of your testing rig, or the Meridian DAC ? If the later, can you measure another DAC, with lower noise floor ?

I would still like to see how those spikes look like with a quality, linear PSU.

BTW - another USB regenerator just hit the market - iFi iUSB 3.0. I have one at home right now. I have posted naked images on CA:

http://www.computeraudiophile.com/f...es-regenerator-xxx-pictures-25985/#post470425
Hi

I also tried the Regen with a 9 volt battery and it made no difference to the spuria. I am making the presumption this is the USB 8kHz data packet noise getting through and nothing to do with the SMPS.
 
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jkeny

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Hi

I also tried the Regen with a 9 volt battery and it made no difference. I am making the presumption this is the USB 8kHz data packet noise getting through and nothing to do with the SMPS.
I agree - using an 11KHz test tone for the measurements might help clarify
 

BE718

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I agree - using an 11KHz test tone for the measurements might help clarify
I agree 12kHz isnt helpful in this instance, however the fact that the 8 and 16kHz tones are not there without the regen and not in the balanced output indicate that this is not jitter or intermodulation or other spuria.
 

jkeny

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I agree 12kHz isnt helpful in this instance, however the fact that the 8 and 16kHz tones are not there without the regen and not in the balanced output indicate that this is not jitter or intermodulation or other spuria.
Yep!
 

BE718

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It would be helpful if all FFT plots came with documentation of how the FFT is calculated. This would include, as a minimum, the number of FFT bins and the window used. Without this information, it is impossible to estimate the "FFT gain" and without this gain information one can mistakenly compare apples to oranges. Other essential information includes the sampling rate and the bit depth. For example, a 44/24 silent track, converted to 44/16 using iZotope dither (set for TPDF) has an FFT noise bins at -137 dBfs using Sony Soundforge with 65K FFT with Blackman Window. Changing to 16K FFT it's more like -131 dBfs. changing to a rectangular window has a smaller effect.

One other thing to worry about is how the FFT bins line up with the signals (or spikes). For example, displaying a 1000 Hz sine wave that peaks at -12 dBfs with the Soundforge 65K Blackman FFT the spectrum shows a peak at -45 dBfs, but if the frequency is shifted to 1004 Hz the peak appears at -12 dBfs, as expected. One needs to know the exact sampling rate of the analyzer to understand if these effects might appear in measurements if one wants to be sure of accurate results when looking at noise spikes (e.g. 8 and 16 kHz spikes that have been discussed). This is an example of how a seemingly irrelevant change in test conditions can create a large and misleading difference in measured results.




Hi

Yes these are all good points. Measurement is a minefield and you need to be aware of the potential issues and pitfalls. The windowing applied will change the amplitudes, have different side lobes to the bin etc etc. A group of very closely spaced signals will get summed into one bin if the resolution is too low leading to one spike of higher amplitude...and so on..... So absolutely, yes I think the test parameters should be posted along with plots :)

FFT gain, useful doc here http://www.analog.com/media/en/training-seminars/tutorials/MT-001.pdf

So we know the PCM4222 rms noise floor is around -122 to 123 dB(A). The theoretical FFT noise floor is therefore 10log10(M/2) dB below the quantization noise floor due to the processing gain of the FFT, where M is the number of points in the FFT (131072), so in my ever inept maths I think thats 48dB. So theoretical FFT noise floor circa 170dB.



So here are the parameters I performed my measurement with:

The ADC is actually a Texas Instruments PCM4222EVM evaluation board.http://www.ti.com/lit/ug/sbau124/sbau124.pdf Cheap as chips, $150, but has pretty much state of the art performance. The inputs are differential. I have built a system around this for two reasons, one as a measurement system as I am into audio electronics, and two as I will be doing some audio/music recording (mic pre-amps being built currently).

PCM4222 is connected to the PC via a Yellowtec AES to USB converter and I am using ARTA software.

Below are plots of the ADC noise floor (red) with the MDAC noise floor (green). 24bit 48kHz (will go higher) . 131072 lines resolution, Kaiser 7 window. 100 linear averages to reduce random noise.

PCM4222 and MDAC noise Floor.jpg


BTW my experience with the regen tends to correlate with Amirs. I think there is a very subtle improvement with it it, however its in the region of being unsure if its entirely my imagination. As a reference the subtle difference between my MDAC output filters are clearly audible to me, however the regen effect is much smaller.
 
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Nov 27, 2013
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Hey Mitch, I am glad you posted here. I always learn so much from your comments.

Maybe you can have a go with the Regen too. Maybe when Amir is done with it, he can send my Regen (in his possession) to you so you can do some null/difference testing with your software and the Hilo. That would be interesting for sure.


Michael.
Some proper null/difference testing will soon be coming along this way :)
 

YashN

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They are so easy to build and seemingly such easy sale that anyone with a soldering iron and screwdriver practically will build one :).
Building a Regen isn't such an easy thing.